The present invention generally relates to a photovoltaic energy system. More specifically, the present invention relates to a photovoltaic energy system that includes a plurality of photovoltaic modules coupled to a power inverter by environmentally protected wiring within a busway such that the photovoltaic system outputs AC power.
Conventional photovoltaic power systems for use in residential and small commercial applications typically include a plurality of interconnected photovoltaic modules mounted on the roof of the residential or commercial building. The interconnected modules are often referred to an array. Each of the photovoltaic modules includes numerous photovoltaic cells that convert solar energy into DC power. Typically, the DC power generated by each of the modules is combined by conventional external wiring and fed to a remote DC to AC power inverter, such as the Series 2400 produced by Omnion Power Engineering Corporation, East Troy, Wis., assignees of the present application. In this type of photovoltaic system, the external wiring carrying the DC power runs from the photovoltaic modules on the roof of the building down to the power inverter, which is mounted either internally or externally to a wall of the building. In most photovoltaic power systems, the power inverter is positioned near the electrical power input to the building from a utility provider, since the AC power output of the power inverter is fed into the distribution panel for the building along with the utility power supply.
Although this type of photovoltaic power system has proved to be an effective way to supplement the electrical energy supplied by the utility provider, the external DC wiring running between the individual photovoltaic modules and from the roof of the building down to the power inverter presents problems during installation of the photovoltaic power system. Since DC wiring is seldom installed in building projects other than photovoltaic systems, electricians more familiar with AC wiring codes and requirements often have difficulty in knowing how to comply with all of the specific building code requirements that accompany the proper installation of DC wiring. Thus, the installation of a photovoltaic power systems having external DC wiring requires the electrician installing the system to expend a significant amount of time reviewing seldom used building code requirements for DC wiring, which increases the cost and time of the installation process.
In addition to the problems caused by the DC wiring during the installation process, the National Electric Code, which is adopted by most local governments, imposes additional requirements on photovoltaic power systems that include external DC wiring running from the photovoltaic modules to the power inverter. The more stringent requirements for external DC wiring mandated by the National Electric Code result in higher system cost due to the additional components and safety devices that must be included in the photovoltaic power system.
One way to alleviate the above-identified installation problems and to avoid the code requirements imposed on photovoltaic systems having external DC wiring is to incorporate a DC to AC power inverter directly into each individual photovoltaic panel. In such a system, such as the Sunsine.TM. 300 manufactured by Ascension Technology, Inc., Waltham, Mass., the DC power generated by each individual photovoltaic panel is converted into AC power within the panel itself, such that an electrician installing the panel does not have to deal with external DC wiring. Although this type of "AC photovoltaic module" functions well and avoids many of the above-identified problems, incorporating a DC to AC power inverter into each individual photovoltaic panel greatly increases the cost of the individual panels as compared to conventional photovoltaic panels that output DC power.
It is therefore an object of the present invention to provide a photovoltaic energy system that combines a plurality of individual photovoltaic modules and a single DC to AC power inverter into an environmentally protected assembly that outputs a supply of AC power. It is a further object of the invention to provide a photovoltaic system that incorporates a busway that interconnects the plurality of individual photovoltaic modules and the power inverter in an environmentally protected manner. It still a further object of the invention to provide a photovoltaic module in which the busway and the individual photovoltaic modules include mating plug members and receptacles that allow the individual modules to be connected to the busway in an environmentally sealed manner. It is still a further object of the invention to provide an DC to AC power inverter that is removably connected to the busway and environmentally protected when attached to the busway, such that the entire DC wiring for the photovoltaic system is concealed and protected.
In yet another object of the invention, the busway includes multiple segments that are each attached to or incorporated within the frame member defining each individual photovoltaic module. It is still a further object of the invention to provide a photovoltaic system in which the busway is formed from joined busway segments that each include an end plug and an end receptacle that allows the busway segments to be connected and environmentally sealed.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.